Internet & the World Wide Web
*
(Explore Cyberspace)
Williams, B.K, Stacy C. Sawyer (2007). Using
Information Technology: A Practical Introduction to Computers & Communications. Seventh Edition,
Outline Materi
Connecting to the Internet
How Does the Internet work?
The World Wide Web
Email & Other Ways of Communicating over the Net
Telephony, Multimedia, Webcasting, Blogs, E-Commerce
Snooping, Spoofing, Phishing, Pharming, Cookies, &
Connecting to the Internet
• Internet History
– Began with 1969’s ARPANET for US Dept. of Defense – 62 computers in 1974
– 500 computers in 1983 – 28,000 computers in 1987
– Early 1990s, multimedia became available on internet
• To connect you need
– An access device (computer)
Connecting to the Internet
Definition:
Bandwidth is an expression of how much data –
text, voice, video and so on – can be sent through a
communications channel in a given amount of time.
Definition:
Baseband is a slow type of connection that
allows only one signal to be transmitted at a time.
Connecting to the Internet
• Data Transmission Speeds
– Originally measured in bits per second (bps)
– 8 bits are needed to send one character, such as A or a
– Currently measured in kilobits per second (Kbps) – Kilo- stands for a thousand
– A 28.8 Kbps modem sends 28,800 bits per second – How many characters per second would that be? – Mbps connections send 1 million bits per second – Gbps connections send 1 billion bits per second
Connecting to the Internet
Modems
– Can be either internal or external to your PC – Most ISPs offer local access numbers
– Need call waiting turned off; either manually or in Windows
High-speed phone lines
Satellite
Cable Modems
– ISDN line
• Integrated Services Digital Network
• Allows voice, video, & data
transmission over copper phone lines
• Can transmit 64 to 128 Kbps
– DSL line
• Uses regular phone lines, DSL modem
• Receives data at 1.5-9 Mbps; sends at 128Kbps – 1.5 Mbps • Is always on
Modems
High-speed phone lines
Modems
– Connects the PC to a cable-TV system
• 2 minutes to download a 2 minute video
High-speed phone lines
Satellite
Cable Modems
Wi-Fi & 3G
Connecting to the Internet
Modems
– Always-on connection using satellite dish to satellite orbiting earth – Send data at 56 – 500 Kbps; receive at 1.5 Mbps
High-speed phone lines
Satellite
Cable Modems
Connecting to the Internet
Modems
– Wi-Fi
• Name for a set of wireless standards set by IEEE • Typically used with laptops that have Wi-Fi hardware
– 3G
• High-speed wireless that does not need access points • Uses cell phones
High-speed phone lines
Satellite
Cable Modems
How Does the Internet Work?
• Internet Access Providers
– Internet Service Providers (ISP)
• Local, regional, or national organization that provides internet access
• Examples: AT&T Worldnet, EarthLink
– Commercial Online Service
• A members-only company that provides specialized content and internet access
• Examples: AOL, MSN
• The internet consists of thousands of smaller
networks
• These link educational, commercial, nonprofit,
and military organizations
• Most are Client/Server networks
– Client: a computer requesting data or services
– Server or Host: a central computer supplying data or services requested of it
How Does the Internet Work?
Point of Presence (POP)
– A local access point to the internet – A local gateway to the ISP’s network
Network Access Point (NAP)
– A routing computer at a point on the internet where several connections come together
– Owned by Network Service Providers (NAP)
– Four major NAPs established in 1993 when the internet was privatized
Private/Peer NAPs (PNAP)
– Established in late 1990s
– Provide more backbone access locations than the
original 4 NAPs in Chicago, Washington D.C., New
Jersey and San Francisco
– >100 in U.S.A. at present
– Facilitate more efficient routing since there are more
backbone access locations
• Internet Backbone
– High-capacity, high-speed data transmission lines – Use the newest technology
– Providers include AT&T, Cable & Wireless, Sprint, Teleglobe, UUNET
• Internet 2
– Cooperative university/business research project
– New standards for large-scale higher-speed data transmission – Requires state-of-the-art infrastructure
• Protocols
– The set of rules a computer follows to electronically transmit data.
– TCP/IP is the internet protocol • Developed in 1978
• Used for all internet transactions
• Packets
– Fixed-length blocks of data for transmission – Data transmissions are broken up into packets
• IP Addresses
– Every device connected to the internet has an address – Each IP address uniquely identifies that device
– The address is four sets of 3-digit numbers separated by periods
• Example: 95.160.10.240
• Each number is between 0 and 255 • Static IP addresses don’t change • Dynamic IP addresses don’t change
• Since addresses are limited, and most PCs are not connected a lot of the time, dynamic addresses are common
• The board of trustees of the Internet Society (ISOC) oversees the standards
• Internet Corporation for Assigned Names and Numbers (ICANN) regulates domain names
• American Registry for Internet Numbers (ARINN) administers the unique IP addresses for North & South America, Caribbean, and sub-Saharan Africa
• Two other organizations administer the unique IP addresses for Europe and the Asia-Pacific region
• Asia Pacific Network Information Center (APNIC)
• Browsers
– Software for web-surfing
– Examples: Internet Explorer, Netscape Navigator, Mozilla FireFox, Opera, Apple Macintosh browser
• Website
– The location on a particular computer that has a unique address
– Example: www.barnesandnoble.com, www.mcgraw-hill.com
– The website could be anywhere – not necessarily at company headquarters
• Web Pages
– The documents and files on a company’s website – Can include text, pictures, sound, and video
• Home page
– The main entry point for the website
– Contains links to other pages on the website
• Uniform Resource Locator (URL)
– A character string that points to a specific piece of information anywhere on the web
– A website’s unique address – It consists of
• The web protocol, http
• The domain name of the web server
• The directory or folder on that server
• The file within the directory, including optional extension • http://www.nps.gov/yose/home.htm
protocol domain name directory file name . extension
• Domain names
– Must be unique
– Identify the website, and the type of site it is • www.whitehouse.gov is NOT the same as
www.whitehouse.org
• .gov means government
• .org means professional or nonprofit organization
Discussion Question: Have you ever mistyped a URL and gone to a website you weren’t expecting? As we learn later in this chapter, some unscrupulous websites take advantage of this.
• HTTP
– The internet protocol used to access the World Wide Web
• HTTPS
– The secure version of HTTP
• Hypertext Markup Language (HTML)
– The language used in writing and publishing web pages
– The set of tags used to specify document structure, formatting, and links to other documents on the web
• Hypertext links connect one web document to another
• Web Browsers
– Your tool for using the internet
– Comes
preinstalled on most PCs
– 5 basic elements
• Menu bar • Toolbar • URL bar • Workspace • Status bar
• Home Page
– The page you see when you open your web browser
– You can change the Home Page on your browser
• Back,Forward, Home &
Search
– Use the menu bar icons to move from one page to another
• Navigation
– History Lists
• A list of websites you visited since you opened up your browser for this session
• Allows you to easily return to a particular site – Bookmarks
• Allows you to store the URL from a site on your PC so you can find it again in another browser session
• To save the URL for a site, click on “Bookmark” in Internet Explorer or Mozilla Firefox
– Or just type in the URL of the page you want to visit
• Web portals
– A gateway website that offers a broad array of resources and services, online shopping malls, email support, community forums, stock quotes, travel info, and links to other categories. – Examples: Yahoo, AOL, Microsoft Network (MSN), Lycos, or
– Most require you to log in, so you can
• Check the home page for general information • Use the subject guide to find a topic you want • Use a keyword to search for a topic
• Search Services
– Organizations that maintain databases accessible through websites to help you find information on the internet
– Examples: portals like Yahoo Search and MSN, and Google, Ask Jeeves, and Gigablast
– Databases are compiled using software programs called spiders • Spiders crawl through the World Wide Web
• Follow links from one page to another • Index the words on that site
• 4 web search tools
– Keyword Indexes
• Type one or more search keywords, and you see web pages “hits” that contain those words
• For phrases with two or more words, put phrase in quotes • Examples are Google, Gigablast, HotBot, MSN Search,
Teoma
– Subject Directories
• Search by selecting lists of categories or topics
• Example sites are Beaucoup, Galaxy, LookSmart, MSN Directory, Netscape, Open Directory Project, Yahoo
– Metasearch Engines
– Specialized Search Engines
• 4 web search tools
– Keyword Indexes
– Subject Directories
– Metasearch Engines
• Allows you to search several search engines
simultaneously
• Examples are Dogpile, Ixquick, Mamma,
MetaCrawler, ProFusion, Search, Vivisimo
– Specialized Search Engines
• Help locate specialized subject matter, like info on
movies, health, jobs
• Multimedia Search Tools
– Allow you to search for nontext resources
Search Tool Site
A9 (Amazon.com) http://a9.com
Blinkx www.blinkx.com
Google www.google.com/video ShadowTV www.shadowtv.com StreamSage www.streamsage.com
Virage www.virage.com
Yahoo! http://video.search.yahoo.com
• Should you trust information you find online?
• There is no central authority that verifies all internet sites
• Guidelines to evaluate Web Resources
– Does the information appear on a professional site maintained by a professional organization?
– Does the website authority appear to be legitimate? – Is the website objective, complete, and current?
2-33
Email & Other Ways of Communicating
over the Net
• Email Program
– Enables you to send email by running email software on your computer that interacts with an email server at your ISP
– Incoming mail is stored on the server in an electronic mailbox – Upon access, mail is sent to your client’s inbox
– Examples: Microsoft’s Outlook Express, Netscape’s Mail, Apple Computer’s Apple Mail, QualComm’s Eudora
2-34
• Web-based Email
– You send and receive messages by
interacting via a browser with a website
– Advantage: You can easily send and receive
messages while traveling
– Examples: Yahoo! Mail, Hotmail, Bluebottle,
Sacmail
2-35
• Using email
1. Get an email address, following the format Joe_Black@earthlink.net.us
2. Type addresses carefully, including capitalization, underscores, and periods
3. Use the reply command to avoid addressing mistakes 4. Use the address-book feature to store email addresses 5. Sort your email into folders or use filters
User Name Domain name
2-36
• Email Attachments
– A copy of a file or document that you send attached to an email to one or more people
– Be careful about opening attachments • Many viruses hide in them
• Know who is sending it to you before you open it
– The recipient must have compatible software to open the
attachment. If they don’t have Excel, they probably can’t read the spreadsheet you sent them.
2-37
• Instant Messaging
– Any user on a given email system can send a message and
have it pop up instantly on the screen of anyone logged into that system
– Examples: AOL Instant Messenger, MSN Messenger, ICQ, AT&T IM Anywhere, Yahoo Messenger
– Not all IM systems interoperate – To get it, you:
• download the software • connect to the internet • register with the service
2-38
Email & Other Ways of
Communicating over the Net
• FTP – File Transfer Protocol
– A software standard for transferring files between computers with different Operating Systems
• Microsoft Windows Linux
• Unix Macintosh OS, and so forth
– You can transfer files from an FTP site on the internet to your PC – Know your FTP site!
• If the FTP site is offering copyrighted material such as music and movies for free, you are breaking US law if you
download files!
2-39
• Newsgroups
– A giant electronic discussion board
– There are thousands of free internet newsgroups
– Usenet is the worldwide public network of servers on the internet www.usenet.com
– To participate you need a newsreader
• Listserv
– An email-based discussion group
– Uses an automatic mailing-list server that sends email to subscribers on selected topics
2-40
• Real-Time Chat (RTC)
– Participants have a typed discussion while online at the same time
– This is not allowed in most college classrooms – IM is one-on-one, but RTC has a list of participants
• Netiquette – appropriate online behavior
– Before you ask a question, consult the FAQ – Avoid flaming
– Don’t SHOUT – use all capital letters – Be careful with jokes
– Don’t send huge file attachments unless requested
2-41
Telephony, Multimedia, Webcasting,
Blogs, E-Commerce
• Internet Telephony
– Uses the internet to make phone calls
– Long-distance calls are either very inexpensive or free
• With no PC, dial a special phone number to packetize your call
• With a PC that has a sound card, microphone, Internet connection, and internet telephone software such as Netscape Conference or Microsoft NetMeeting
2-42
• Multimedia on the Web
– Allows you to get images, sound, video, and animation – May require a plug-in, player, or viewer
• A program that adds a specific feature to a browser so it can view certain files
• Example: Adobe Acrobat Reader, RealPlayer, QuickTime – Multimedia Applets
• Small programs that can be quickly downloaded and run by most browsers
• Java is the most common Applet language
• Microsoft’s Visual Studio creates ActiveX and com objects
2-43
• Multimedia on the Web
– Animation
• The rapid sequencing of still images to create the appearance of motion
• Used in video games and web images that seem to move – Video
• Streaming video is process of transferring data in a
continuous flow so you can begin viewing a file before it is all completely sent
– Audio may be transmitted either:
• Downloaded completely before the file can be played, or • Downloaded as streaming audio
2-44
•
RSS newsreaders
– Programs that scour the web and pull together “feeds” from several websites to one place
•
Blog
– Short for web log, a diary-style web page
– Have become popular, both privately and in politics
•
Podcasting
– Recording internet radio or similar internet audio programs – Some radio stations webcast their audio programs over the
internet
2-45
•
E-Commerce
– Conducting business activities online
– B2B Commerce is business-to-business e-commerce
– Online Finance now involves online banking, stock trading online, and e-money such as PayPal
– Online auctions link buyers with sellers
• eBay is the most well-known example of person-to-person auctions
• OnSale is a vendor-based auction that buys merchandise and sells it at a discount
• Priceline is an auction site for airline tickets and other items
2-46
Snooping, Spoofing, Phishing, Pharming,
Cookies, & Spyware
• The internet was founded as a collaborative tool
based on trust
• Not everyone on the internet is honest
• Snooping
– Email is not private
• Corporate management has the right to view employees’ email
• Email that travels over the internet may be captured and monitored and read by someone else
2-47
•
Spam: Electronic Junk Mail
– Unsolicited email that takes up your time and may carry viruses or spyware
– Delete it without opening the message – Never reply to a spam message
– When you sign up for something, don’t give your email address – Use spam filters
– Fight back by reporting new spammers to www.abuse.net or www.spamhaus.org or www.rahul.net/falk
2-48
•
Spoofing
– Using fake email sender names so the message appears to be from a different source, so you will trust it.
– If you don’t know the sender, don’t open it.
•
Phishing
– Using trusted institutional names to elicit confidential information – Some common schemes look like they are from your bank or
from eBay and ask you to “update” your account.
– Don’t do it – the legitimate company already knows your account information!
– If you want to update your information, CALL the number in the phone book, not the number in the email!
2-49
•
Pharming
– Redirecting you to an imposter web page.
– Thieves implant malicious software on your PC
– Redirects you to an imposter web page even when
you type the correct URL!
– To foil it, type the URL with https first (for http secure)
https://www.microsoft.com Use this one with https,
not
http://www.microsoft.com Since it has http, it could be
spoofed
2-50
• Cookies
– Little text files left on your hard disk by some
websites you visit
– Can include your log-in name, password, and
browser preferences
– Can be convenient
– But they can be used to gather information
about you and your browsing habits
2-51
•
Spyware
– Applications that download without your knowledge
– They hide on your PC and capture information about
what is on the PC and what you are doing
– That information is then transmitted to the spyware
master’s website on the internet
– Information may be used against you to steal your
identity, get credit cards in your name, or for other
crimes
2-52
•
Spyware (continued)
– To prevent spyware, you must install and use
“Antispyware software” at all times
– Examples: Ad Aware, AntiSpyware, Spybot Search &
Destroy, Pest Patrol, SpyCatcher, Yahoo toolbar with
Anti-Spy
– Be careful about free and illegal downloads since they
are a source of spyware
– Don’t say “I agree” when you are downloading
something – read the fine print
– Beware of unsolicited downloads
